Yes, at least on the vectra B.
The thermostat should start to open at 92 deg C. and be fully open at 107 deg C.
In normal driving it should not get so hot that the radiator fan starts to run, which is at 100 deg C.
If this is happening you may have a faulty thermostat, a partially blocked radiator or a failing coolant pump.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix cars.